Centimeters of mercury to millimeters of mercury converter on this page calculates how many millimeters of mercury are in 'X' centimeters of mercury (where 'X' is the number of centimeters of mercury to convert to millimeters of mercury). In order to convert a value from centimeters of mercury to millimeters of mercury (from cmHg to mmHg) simply type the number of cmHg to be converted to mmHg and then click on the 'convert' button.